Hemilabile Proton Relays and Redox Activity Lead to {FeNO} x and Significant Rate Enhancements in NO2 – Reduction

Incorporation of the triad of redox activity, hemilability, and proton responsivity into a single ligand scaffold is reported. Due to this triad, the complexes Fe­(PyrrPDI)­(CO)2 (3) and Fe­(MorPDI)­(CO)2 (4) display 40-fold enhancements in the initial rate of NO2 – reduction, with respect to Fe­(Me...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2018-12, Vol.140 (49), p.17040-17050
Main Authors: Cheung, Pui Man, Burns, Kyle T, Kwon, Yubin M, Deshaye, Megan Y, Aguayo, Kristopher J, Oswald, Victoria F, Seda, Takele, Zakharov, Lev N, Kowalczyk, Tim, Gilbertson, John D
Format: Article
Language:English
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Summary:Incorporation of the triad of redox activity, hemilability, and proton responsivity into a single ligand scaffold is reported. Due to this triad, the complexes Fe­(PyrrPDI)­(CO)2 (3) and Fe­(MorPDI)­(CO)2 (4) display 40-fold enhancements in the initial rate of NO2 – reduction, with respect to Fe­(MeOPDI)­(CO)2 (7). Utilizing the proper sterics and pK a of the pendant base(s) to introduce hemilability into our ligand scaffolds, we report unusual {FeNO} x mononitrosyl iron complexes (MNICs) as intermediates in the NO2 – reduction reaction. The {FeNO} x species behave spectroscopically and computationally similar to {FeNO}7, an unusual intermediate-spin Fe­(III) coupled to triplet NO– and a singly reduced PDI ligand. These {FeNO} x MNICs facilitate enhancements in the initial rate.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.8b08520